284 



THE BRYOPHYTES 



on the upper surface of the receptacle, and the youngest anther- 

 idia are found nearest the notches which mark the position of 

 the growing points along the edge of the disk. The archegonial 

 receptacle (Fig. 250) is larger than the antheridial, and the top 

 is bent back into several long, finger-like projections like the 

 ribs of an umbrella. Numerous archegonia are formed in lines 

 (Fig. 251, A) on the under side between the lobes, and are pro- 

 tected by singular fringes. The youngest archegonia are formed 



FIG. 252. Sporophytes and receptacles of Marchantia 



A, lower view of an old female receptacle, showing the sporophytes in rows between 

 the fringes /, like peas in a pod. B, section of a receptacle (diagrammatic), 

 showing a mature sporophyte anchored by its foot and projecting beyond the 

 fringe /: the spore case is open, exposing the mass of elaters el; a young 

 sporophyte is shown at the right still inclosed within the archegonium (ca- 

 lyptra) ; e, special envelopes around the archegonia and sporophytes 



nearest the stalk, so that the older ones lie farther out, an 

 arrangement exactly opposite from that of the antheridia. This 

 is explained by the fact that the growing points which lie be- 

 tween the lobes grow downward and underneath towards the 

 stalk. The edge of the disk is thus bent back on itself, and the 

 lower surface is really an extension of the upper surface. 



A number of archegonia may be fertilized in Marchantia, and 

 their eggs then develop sporophytes in radiating rows on the 



